The first nine months of the energy supplement were paid in a lump sum before the start of the carbon tax on July 1.

From Wednesday, the supplement will be paid each fortnight along with the pension. The Coalition has promised to remove it should it take office and abolish the carbon tax.

But unemployed Australians on Newstart will get much less. The single Newstart benefit will climb by $4.40 a fortnight. The Newstart carbon energy supplement is $8.40 per fortnight.

The combination means unemployed Australians will get just a third of the increase offered to pensioners on Wednesday: $12.80 per fortnight instead of $35.80.

Originally in line with the pension, Newstart began slipping in 1997 when the Howard government guaranteed to index the pension by at least the increase in male earnings but left Newstart linked to the consumer price index.

CPI has climbed little since. In the year to December, it grew 2.2 per cent while male earnings climbed 5.5 per cent.

From Wednesday, the single Newstart payment will be $497 per fortnight. The pension will be $794.90. Labor backbenchers are lobbying Treasurer Wayne Swan to announce a $100 per fortnight increase in Newstart in the May budget. It would cost $1.2 billion per year.